Authors:

Enrico Fonda
(Universit\'a di Trieste; University of Maryland at College Park)

Matthew Paoletti
(University of Maryland, College Park)

Daniel Lathrop
(University of Maryland, College Park)

Katepalli Sreenivasan
(International Centre for Theoretical Physics; University of Maryland at College Park)

In 1955, Feynman theorized that the lowest energy state of rotating
superfluid helium would result in a lattice structure of
quantized vortices.
In 1979, Yarmchuk \textit{et. al.} observed a small lattice array
of up to eleven vortices
using clusters of ions, and later experiments observed the
lattice array in
superfluid $^{4}$He perpendicular to the axis of rotation using
hydrogen ice
particles (Bewley \textit{et. al.} 2006). Yet, the formation and
dynamics of these arrays
remain otherwise unexplored experimentally. Now, by visualizing
sub-micron
particles trapped on quantized vortices, we characterize the
lattice array
formation in superfluid helium. Our study investigates the
lattice formation
by independently varying rotation rate and temperature.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.DFD.ET.3